A novel electromagnetic nondestructive testing method for carbon fiber reinforced polymer laminates based on power loss

Carbon fiber reinforced polymer (CFRP) is electrically conductive, so eddy-current testing (ECT) method can be used for non-destructive testing (NDT) of CFRP. However, due to the low bulk conductivity of CFRP, the highfrequency systems are considered more suitable in conventional ECT method. But high-frequency systems are more difficult to build and implement. Concerning this issue, a novel CFRP non-destructive testing method with working frequency up to 750 kHz is proposed in this paper. The method is based on power loss of the micro-probe, which makes use of Joule heat generated by the eddy-current in carbon fibers. The method is combination of ECT and thermography principle, which not only maintains higher signal-to-noise ratio at low frequency but also avoids the problems caused by high frequency. An experimental setup using C-Scan technique was built. Scanning experiments on orthogonally woven laminates, two-directional laminates, four-directional laminates and unidirectional laminates at various working frequencies including 750 kHz were carried out. Scanning results prove that the method can detect the cracks and fiber distribution of CFRP at low frequency up to 750 kHz, and has a good signal-to-noise ratio.

Automated summary

The novel CFRP non-destructive testing method proposed in this paper utilizes a working frequency up to 750 kHz to detect cracks and fiber distribution, with a good signal-to-noise ratio.